- The MPI CyberMotion Simulator with its 8 independent axes
Sustained accelerations are usually simulated by use of motion cueing algorithms that involve washout filters. Using these algorithms, a fraction of the gravity vector generates the sensation of acceleration by an unperceived backward tilt of the cabin. A different solution to simulate sustained accelerations involves centrifugal force. If a subject is rotated continuously, the canal system adapts and the centrifugal force generates the perception of an ongoing acceleration. Both solutions require the subject to be seated in a closed cabin because the visual system would otherwise destroy the illusion.
To achieve continuous rotation around the base axis, the robot arm was modified by the manufacturer (KUKA robot AG, Germany). The robot was equipped with a different transmission and further mechanical modifications. Motor power and electrical control signals are transmitted to the robot by slip rings, an outer slip ring for power lines and an inner slip ring for high frequency signals.
In its standard configuration, the cabin is attached to the robot flange from behind. In this configuration the subject faces outwards and it is possible to simulate constant deceleration by rotating the robot around its base axis. The 6 axes of the original robot did not allow the possibility to place the subject facing inwards towards the base of the robot, so as to simulate constant acceleration. In order to achieve this possibility, the cabin was equipped with an actuated seventh axis. The C-shaped axis, along which the cabin can slide, provides the possibility to steer the robot into a position in which the cabin is attached to the robot flange from below. In this configuration, turning the last robot axis allows placing the subject towards the center of rotation that in turn grants the possibility to simulate a constant acceleration or head-centered yaw rotation.
The robot is equipped with its 6 axis controller and the 7th axis is equipped with a self developed separate controller. To achieve synchronized operation of the full 7 axis system, a combined control system was developed. This control system also monitors and supervises all safety devices and offers the possibility for manual and automated control of the MPI CyberMotion Simulator.